Effect of electron irradiation on (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$ from London penetration depth measurements

ORAL

Abstract

The effects of artificial disorder induced by 2.5 MeV electron irradiation on superconducting properties of single crystals of (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$ (fifteen different compositions covering a wide interval of $0.20 \leq x \leq 1.0$) was systematically studied by tunnel-diode resonator measurements of the in-plane London penetration depth, $\lambda(T)$, down to ~50 mK before and after irradiation. Upon electron irradiation (with total doses up to $2\times 10^{19}$ $e^-$/cm$^2$), the increase of resistivity at \(T_{c}\), $\Delta \rho (T = T_{c })$ and the decrease of $\Delta T_{c} / T_{c0}$ was largest at heavily over-doped compositions. A non-exponential behavior in samples with $x \geq 0.8$ was found from the low-temperature variation of $\lambda(T)$ suggesting a change in the superconducting gap structure or peculiarities of (inter-, intra-) band scattering and pairing. We will discuss possible scenarios to connect a fully gapped state at the optimal doping ($x\approx 0.40$) with the apparent nodal behavior in the heavily over-doped region ($x \geq 0.8$).\\\\ The work performed in Ames Lab and Iowa State University was supported by the U.S. DOE, OS, MSED under contract DE-AC02-07CH11358. The work performed in University of Florida was supported by NSF-DMR-1005625.

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Authors

  • K Cho

    Ames Laboratory and Iowa State University, USA, Ames Laboratory and Iowa State University

  • Serafim Teknowijoyo

    Ames Laboratory and Iowa State University, USA, Ames Laboratory and Iowa State University

  • Makariy Tanatar

    Ames Laboratory and Iowa State University, USA, Ames Laboratory

  • Yong Liu

    Ames Laboratory and Iowa State University, USA, Ames Lab

  • Thomas Lograsso

    Ames Laboratory and Iowa State University, USA, Ames Lab

  • R Prozorov

    The Ames Laboratory and Iowa State University, Ames Laboratory and Iowa State University, USA, Ames Laboratory and Iowa State University

  • Marcin Konczykowski

    Ecole Polytechnique, France, Ecole Polytechnique

  • Saurabh Maiti

    University of Florida, USA, University of Florida

  • Peter Hirschfeld

    University of Florida, University of Florida, USA

  • Vivek Mishra

    Oak Ridge National Laboratory, USA, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN-37831, USA.